This present invention is an improved closed cell composite fabric, providing more thermal resistance and reduced heat loss than other closed cell composites of comparable width, while also being lighter and optionally breathable. This present invention shows how closed cell foam, in either perforated or non-perforated form, can be combined with one or two substrates, with at least one of these substrates metalized to also act as a radiant barrier. The composite has laminated outer textile layers appropriate to the application, such as Nylon for outer layers or fleece for inner layers, together with any additional functionalization, such as hydrophobic or antibacterial coating.
In the present invention the use of metallization to create infrared reflecting barriers is adopted for watersports apparel, clothing or outdoor equipment such as sleeping bags or tents. Corrosion, particularly in salty environments, of these metal layers through oxidisation can be considerable and methods known in the art are adopted to help prevent oxidisation. These radiant barriers, however, also require careful insulation from heat loss via conduction, and moisture management to help keep emissivity low.
When a moisture vapor permeable substrate is coated over substantially an entire surface using conventional methods such as air knife coating, flexographic printing, gravure coating, etc., the coating reduces the moisture vapor permeability of the substrate. If the starting substrate has an open structure and is highly air permeable, the substrate can retain sufficient moisture vapor permeability after coating to be useful in certain end uses, such as apparel. For example, fabrics described in U.S. Pat. No. 5,955,175 to Culler are both air permeable and moisture vapor permeable after being metalized and coated with an oleophobic coating.
When the starting moisture vapor permeable substrate is a non-porous monolithic membrane, conventional coatings result in significant covering of the surface of the substrate. This results in a coated substrate having significantly lower moisture vapor permeability than the starting substrate. This is undesirable in apparel or outdoor equipment products, which are desirably permeable to moisture vapor while at the same time forming a barrier to infiltration by air and water. As described by Sympatex in U.S. Pat. No. 6,800,573 it is possible to coat these non-porous vapour permeable substrates using a plasma cleaned vapour deposition metalization process and maintain good vapour permeability.
US Patent Application Publication US 2004/0213918 A1 (Mikhael et al.) discloses a process for functionalizing a porous substrate, such as a nonwoven fabric or paper, with a layer of polymer, and optionally a layer of metal or ceramic. According to one embodiment, the process includes the steps of flash evaporating a monomer having a desired functionality in a vacuum chamber to produce a vapor, condensing the vapor on the porous substrate to produce a film of the monomer on the porous substrate, curing the film to produce a functionalized polymeric layer on the porous substrate, vacuum depositing an inorganic layer over the polymer layer, and flash evaporating and condensing a second film of monomer on the inorganic layer and curing the second film to produce a second polymeric layer on the inorganic layer. Mikhael et al. also discloses another embodiment including the steps of flash evaporating and condensing a first film of monomer on the porous substrate to produce a first film of the monomer on the porous substrate, curing the film to produce a functionalized polymeric layer on the porous substrate, vacuum depositing a metal layer over the polymer layer, and flash evaporating and condensing a second film of monomer on the metal layer and curing the second film to produce a second polymeric layer on the metal layer.
US Patent Applications US 2007/0166528 A1 (Barnes et al.) discloses a process for oxidising the surface of a metal coating with an oxygen-containing plasma to form a synthetic metal oxide coating, making a superior resistance to corrosion of the metallized porous sheet. These sheets, however, are micro-porous and less durable than can be constructed by non-porous monolithic membranes.
It would be desirable to provide metallized fabrics that have good protection against oxidation while not sacrificing high moisture vapor permeability for uses requiring good thermal barrier properties such as clothing, sleeping bags and tents.
Methods for both improving the moisture vapour permeability of the composite and insulating the metal layer from conduction are disclosed in PCT application No. PCT/IB2011/002872 (Conolly et al). Conolly achieved this by covering the substrate first with a textile prior to metallization, where this textile is then preferably a very open pore structure, such that the metallization coats through the air gaps of the textile onto the substrate layer. Methods for managing the infra red emissivity of the metal layer are also disclosed by Conolly, achieved by protecting the metal layer from moisture, where the textile is preferably high wicking/hydrophilic and the metal layer is coated for water and/or oil repellent functionality.
U.S. Pat. No. 4,136,222 (Jonnes) describes a thermally insulating sheet material where a specularly reflective sheet material, between 2.5 mm and 10.5 mm, is supported in spaced relation from a thermally radiating surface by an array of resiliently flexible and compressible polymeric foam segments that cover only a portion of the area of the sheet. Jonnes explains that none of the prior art is acceptable for commercial insulation for garments, as the structures are all too rigid and his invention avoids such deficiencies by use of a novel separator layer.
U.S. Pat. No. 4,583,247 (Fingerhut), describes an improvement to Jonnes, utilizing a substantially continuous, yet porous, interlining sheet material with the reflective sheet material facing outwards, adhered at spaced intervals, and preferably protected from oxidisation with an outer layer of transparent material comprising a clear plastic film.
In both U.S. Pat. Nos. 4,136,222 and 4,583,247 the spacer fabric is fundamentally porous, and the protection from oxidisation proposed by U.S. Pat. No. 4,583,247 adds too much bulk to the composite.
In the current invention, a closed cell foam, such as neoprene foam, is used as the insulating layer for the metal layer radiant barrier. The metal layer has low emissivity and can be facing towards the closed cell foam. It has been shown that even with unperforated closed cell foam that this structure measures to a higher thermal resistance with a metal layer radiant barrier. It has also been shown that when the closed cell foam is highly perforated that the metal layer is a more effective radiant barrier in the composite.
In the current invention, through the use of a closed cell spacer structure, there is resilience to the total fabric from filling with water if there is an accidental puncture of the fabric through use.
Methods for both improving the moisture vapour permeability of the composite and insulating the metal layer from conduction are disclosed in the present invention. This can be achieved by covering the substrate first with a textile prior to metallization, where this textile is then preferably a very open pore structure, such that the metallization coats through the air gaps of the textile onto the substrate layer. Methods for managing the infra red emissivity of the metal layer are also disclosed, achieved by protecting the metal layer from moisture, where the textile is preferably high wicking/hydrophilic and the metal layer is coated for water and/or oil repellent functionality.